Stumped With Audio Issue (Constant Buzzing Only From Computer)
 

I just picked up a 7.1 system, Panasonic SC-HT200 and hooked it up to my computer via RCA audio cables.

There's a constant buzzing coming from the subwoofer, doesn't matter if I mute all sounds from the computer, the buzzing doesn't go away. Checked that the plug is fully inserted. Tested the same RCA cable by hooking up the Xbox 360 to the sound system, and there's no buzzing. Checked other audio sources and the speakers and sub work fine when playing a DVD or using hte ipod dock.

What the heck is the signal coming from the computer that's causing the subwoofer to buzz, even when nothing is playing? I have an Auzentech X-Plosion soundcard, my old speakers work just fine using the same connection (no buzzing). I'm really really stumped.

I had a problem similar to this once, I found out that it was the S/PDIF cable from the DVD drive to my sound card. Once I unplugged it the noise went away.

I guess there was some sort of ground loop happening over that particular cable...

it's either noise picked up by the cable, or, more likely noise getting picked up by your line-in jack. the cable from my tv tuner to my line in picks up tonnes of noise, so I keep it muted in Windows when I'm not using the tuner, and the buzzing is gone.

optical isnt supposed to have ground loop

buzzing is due to one of the following:

bad shielding on rca
rca outs / 3.5mm out on computer has a noisy amp

your amplifier is much more sensitive than that of basic computer speakers

use the optical or coaxial out

You can get interference if your speakers have a 3 prong power plug, which are connected to the same power bar as your computer.

I know many audio guys cut the center grounding prong from their equipment to reduce noise.